Hello.
I can only connect one PC to the internet at the same time.
All others get no DNS Adress whatever I tried.
But each and every PC gets full access if connected alone. So I connect and disconnect them 20 times a day, ennoying !
I have simply an 8 port switch on the modem and for long times this runs without problems.
None of my friends can help me anymore.

Anyone here who is expert for those things ?

Please write a pm, maybe I can give you remote control over my boxes.